ML20002E009

Stress Levels & Design Practices for Stainless Steel Parts in Cpc,Big Rock Plant,Reactor Vessel & Steam Drum

ML20002E009
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	01/12/1971
From:	Pierson T ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY
To:
Shared Package
ML20002E008	List: ML20002E007 ML20002E009
References
6460-A, NUDOCS 8101260070
Download: ML20002E009 (17)

Text

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REPORT 6460-A g c. f ib' Regulatory Fife Cy.

Emtred wett: ndst / /# 7/

COMBUSTION ENGINEERING, INC.

NUCLEAR CCMPONENTS DEPARTMENT CE CO:iTRACTS 6460D AND 6460R CE WORK ORDER A98449 STRESS LEVELS AND DESIGN PRACTICES FOR STAINLESS STEEL PARTS IN CONSUMERS POWER, 3IG ROCK PLAh'I', REACTOR VESSEL AND STEAM DRUM T. M. PIERSON Ple/2&oo10

ABSTRACT ~

As' requested by General-Electric,'information on stainless steel parts - subjected to furnace stress relief and used in the - fabrication of the. Consumers Power - Big-Rock ' Plant -

Reactor Vessel and Steam Drum is. presented in this report. -

Included are stress levels in nozzle extensions -in the reactor vessel. and steam drum,- and 'in internal brackets in the reactor zvessel.

In addition, a statement of design practices applied-in defining requirements for internal brackets in the stean drum is provided.

SIGNIFICANT RESULTS Stress levels in each of the parts defined by General Electric (Reference 1) are summarized as follows:

Stress Intensity (ksi)

Part Description Membrane Peak Alternating Downcomer Nozzle Extension 11.2

'10.1 13 1 Riser' Uozzle Extension 99 8.9 53 Vent Nozzle Extension 51 57 10.2 Instrument Nozzle Extension 91 8.7 6.2 Steam Outlet Nozzle Extension 10.0 9.6 6.3 Letdown Nozzle Extension 9.o 8.7 6.4 Recirculation Nozzle Extension 10.5 10.1 6.6 Poison Nozzle Extension 91 8.8 4.9 Core Support Bracket 4.0 11.8

<11.8 Core Support Plate Bracket 1.4 15.7

<l5 7 Diffuser Bracket 05 39

<39 Vent Nozzle Flange 7.2 58 57 All calculated stresses are less than the allowable values of of 14.8 ksi for membrane stress intensity, 16.2 ksi for peak stress intensity, and the material endurance limit of 18.1 ksi.

Evaluation of' design practices used for the steam drum shows:

1.

Design of internals utilizes design concepts developed for conventional fuel power plants, 2.

Design, material, and fabrication conforns with ASME specifications applicable at the time of fabrication of the subject unit.

3 The desico-concept minimizes loads in internals, and their supports by requiring sliding joints between ma-terials of different coefficients of thermal expansion.

1

-r TABLE OF CONTENTS ABSTRACT........................................./....

1 SIGNIFICANT RESULTS....................................

1

1.0 INTRODUCTION

3

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1.1 Stress Leve1s...............................

3 1.2 Design Practices............................

3

. 2.0 STRESS LEVELS....................................

4 2.1 Nozzle Extensions-...........................

5 2.2 Internal Brackets..........................

11 2.2.1 Core Support Bracket......

11 2.2.2 Core Support Plate Bracket 12 J

2.2.3 Diffuser Bracket....................

13 23: Vent Nozzle F1ange,.........................

13 30 DESIGN PRACTICES................................

14-

4.0 REFERENCES

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. APPENDIX A - STRESS C ALC ULATIONS...................... A-1 2

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1.0.

INTRODUCTION

-Information on stainless steel parts subjected to furnace stress

~

relief and used in ' fabrication of the Consumers Power, Big Rock Plant, reactor vessel and steam drum, as requested by General Electric (Ref.1) is reported herein. ' Information included is as follows:

1.1 Stress Levels Levels of stress in nozzle extension in the reactor vessel _and steam drum, and in internal brackets in the reactor vessel are required.

Specific parts for which-

. stress levels have been requested are:

Part P/N Ref. Dwg.

Steam Drum Downcomer Nozzle Extension 103-3 E230-103 Eiser Nozzle i tension 103-8 E230-103 Vent Nozzle L t nsion 104-7 E230-104 Reactor Vessel Instrument Nozzle Extension 795-4 E201-795

- Steam Outlet Nozzle Extension 795-13 E201-795 Letdown Nozzle Extension 795-17 E201-795 Recirculation Nozzle Extension 796-3 E201-796' Poison Nozzle Extension 796-8 E201-796 Core Support Bracket 802-15/16 E201-802 Core Support Plate Bracket 802-18 E201-802 Diffuser Bracket 802-32 E201-802 Vent Nozzle Flange 807-3 E201-807 s

1.2 Design Practices A statement on design practices used in design of internal brackets in the steam drum is required.

Specific parts considered in +he statement include:

Part P/N, Ref. Dwg.

Downcomer Baffle Assy.

6./67A E2'30L-108 Screen Dryer Hanger Lug 79 E230-108 Feedwater Header Supports 85A E230-108 3

W W

b 2.0.' STRESS LEVELS Categories of stress, and acceptability criteria for each category used in defining stress levels presented in this report are the same as.used for original design of the vessels.

These stress 1 categories were initially defined by specifications

.for each of the vessels (Refs. 2 and 3) and further clarified by Combus tion Engineering- (Refs. 4 and 5).

. In general, the stress criteria conforms to1that given in

" Tentative Structural Design Basis," Department of Commerce Bulletin PB151937- (Ref.10) except for nomenclature.

The nomen-clature used herein has been purposely kept the same as that of the original analysis so as to minimize possible confusion be tween the.s tress categories.

Stress categories are expressed in terms of " stress intensity" which is defined as the difference between the algebraically largest principal stress and the algebraically smallest prin-cipal stress.

The ' "s tress intensity" is numerically equal to twice the maximum shear stress.

Each-category of stress reported herein, and its acceptability criteria is as follows:

.M~.mbrane Stress -Intensity--the - s tress intensity derived from the average values of principal stress across the thickness of a section that is subjected to internal pressure, techanical forces, or their combinations (neglecting effects of structural discontinuities and stress concentrations).

The membrane stress intensity is limited to the allowable value of stress from Table P-7,Section I, ASME Code (Ref. 7) for the material at the temperature that the loads are applied.

Peak Stress Intensity--the stress intensity derived from the highest values of principal stress at any point across the thickness of a section that is subjected to internal pressure, mechanical forces, or their combina-tions, including the effects of structural discontinuities but not stress concentratichs.

The peak stress intensity is limit:d to 90% of the material yield strength at the temperature at which the loads are applied.

Values of material yield strength are taken from Table 5-1,

" Tentative Struc tural Design Basis," Department of Commerce Eulletin PB151987 (Ref.10).

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2.0 ' STRESS LEVELS _ (c'ontinued)

Thermal' Stresses--no -stress limitations are applied to thermal stresses.

Thermal stresses are considered as transient ' stresses and.are. combined with-peak stresses for-cyclic evaluation.

Alternating Stress Intensity--one-half of the algebraic difference between the= maximum and minimum stress inten-

- sities at a' point in a'section during a cycle of transient

. operation.

Maximum and minimum stress intensities are derived from the principal stresses at the point when the structure is subjected to internal pressure, mechanical forces, thermal stresses, and include the effects of structural discontinuities and stress concentrations.

Alternating stress intensity. is used to evaluate possible.

limitations which might result from material fatigue.

This evaluation is accomplished by comparing the required number of cycles of an operating condition to the allowa-ble cycles for the maximum alternating stress for the condition..The allowable number of alternating stress cycles is obtained from Figure 5.2-3, " Tentative Struc-tural Design Basis", Department of Commerce Bulletin PB151987 (Ref. 10).

For combinations of operating cycles, the total fatigue effect on the material is calculated as the sum of the ratios of required cycles to allowable cycles for each i

condition.

This sum is defined as usage factor and is limited to.a maximum value of 0.8.

2.1 Nozzle. Extensions Since primary loads in the nozzle extensions are limited to internal pressure, membrane stress intensities are calculated by classical equations for a thin wailed cylindrical shell subjected to internal pressure.

b The Seal-Shell - 2 Computer Program (Ref. 11) is used to calculate peak stress intensities, cnd the principal stresses needed to determine alternating. stress intensities, in the nozzle extensions.

Use of this program. requires that. the actual structure be represented lur an analytical model.

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e 2.0' STRESS ~ LEVELS 2. l'

ozzle Extensions (continued)

The 'todel used in analysis of the nozzle extensions. (Fig.

I) consists'of a cylindrical section capped at each~end.

' Geometry of the cylindrical sec tion conforms to the K"8-actual geometry of the nozzle body and nozzle extension.

Lengths of the sections between

'N the caps and the nearest dis-s continuity is taken as B. =

3 0 so as to minimize carry

)\\

over effects.

The caps are g

used to insure proper repre-4 sentation of stresses due to~

pressure blow-off-loads.

jr #

The analytical model is divided into nodal segments (2 g Kg100).

j Radius (R), elevation (Z) and l

thickness is defined for each r

I nodn.

Physical properties of I

th.- nodes are taken from "C antative Structural Design l

Basis" (Ref. 10) at the average j

coolant temperature for tran-

! /

sient conditions.

The value I

of coefficient of thermal l

expansion used is the mean value for steady state conci-

"12 e

tions and the instantaneous value for transient conditions.

Loading conditions used in cal-4 y

'culation of stress levels in the

+E nozzle. extensions are as define /.

by specifications used in design of the vessels except that actual operating pressure of 1350 psia is used.

FIGURE I Troical Analvtical-Model f

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2.0 STRESS LEVELS

.2.1 poy le Extensions (continued)

These operating conditions are:

Design Condition Dasign Pressure P = 1700 psia Design Temperature T = Saturation (6140F)

Normal Operating Condition Operating Pressure P = 1350 psia (1335 psis)

Operating Temperature T = Saturation (5820F)

Transient Conditions Normal Startup (2100 occurrences)

Pressure P = O-1335 psis Temperature T = 100 - 582 F at 100 F/hr 0

Normal Shutdown (2000 occurrences)

Pressure P = 1335-O psis 0

Tenperature T = 582 - 100 F at 100 F/hr Emergency Shutdown (100 occurrences)

P re s sure -

P = 1335 - 0 psis Temperature T =.582 - 212oF at 3820F/hr for steam drum, 300 F/hr for reactor vessel Since required number of occurences of transient conditions are not defined for the reactor vessel, they are assumed to be the same as for the steam drum.

Pipe reactions were not provided by vessel specificatf ons, J

and ale not available at this time, so have not been con-sidered in this report.

Loads applied to the analytical..models are derived from the loading conditions as follows:

Internal Pressure--applied as a uniform load dis-tributed over the inside surface of the analytical model.

For transient operations, the applied uniform Koad is taken as equal to the pressure at the end of the' transient.

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'2.O ~ STRESS LEVELS 2.1 Hozzle Extensions Internal Pressure.(continued)

Thus, pressure.is 1700 psi for design, 1335 psi for steady state-operation and for startup, and 0 psi for both normal and emergency shutdown.

Thermal Loads--applied to the analytical model in the form of temperatures across the thickness of each section.

For the Seal-Shell program, tempe ratures are required at the inner surface (T1), quarter thick-ness (Tg 4), half thicknese (Tv a), three-quarter thickness (Ts/ 4) and outer surface (T ).

Temperatures O

for use. in the calculations are obtained from the -

equation dT 1 DT gr-g- = 0 which has the solution Tx = T +Cmt o

where Tx =' Temperature at point x (OF)

To = Uniform initial temperature (OF) te = Effective thickness (ft)

= t for one material slab

= Jt a + t2~l17E2 12 tTf2~k /k2 for bi-metal slLb i

i

= Jta + 0 79375t + 0.06138 for carbon steel clad -

with 5/32" of 304 S.S. at 350 F

& = Thermal diffusivity of slab (f t2/hr) m = rate of coolant temperature change (O /hr)

F Time from start of transient (hr)

T=

Npo = Fourier Modulus = &T/te2 and

(

- 2

• Ngo Fo e

-(n+f)y NFo sin (n+d)vk

=

I

+7 n=0 (n'+

)3 8

{. -

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t I

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2.0 -STRESS' LEVELS

=

2.1 Mozzle Extensions Thermal Loads (continued)

This solution involves the following assumptions:

1.

One dimensional heat flow.

2.

Thermal properties constant and uniform throughout the structure at the average coolant temperature.

3 Infinite heat transfer at surface in contact with coolant.

Other surfaces perfectly insulated.

In addition, application of this method of solution to the structure being analyzed include the assumptions that the axial temperature distribution in each section of constant thickness is uniform along the length of the section and that changes in temperature distribution between sections of different thickness is uniform along the length of the structural transition.

In applying this temperature solution, it can be seen that the temperature difference across the thickness of a sec-tion decreases with increasing value of Fourier Modulus (Nyo).

Thus,since for a value of Nyo of 40, the temper-atu~e difference across the section is only 1.25% of the totml coolant temperature change, it is within the accuracy of the solution to assume the temperature across any section with a value of Ngo ;) 40 to be constant at the coolant temperature.

Mechanical Load--limited to pipe reactions which are not available at this time.

Thus, mechanical loads are not considered in the calculation' of stress levels in the nozzle extensions.

Stress levels in the nozzle extensions are determined as follows:

Membrane Stress Intensities--as previously stated, limiting primary loads in the nozzle extensions to internal pressure allows membrane stress intensities 9

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2.0 STRESS' LEVELS

. 2.1 Nozzle Extensions Membrane Stress Intensities _ (continued) to be ceiculated by use of classical equations for a thin-walled cylinder subjected to internal pressure.

i Thus, where ar=-

az=

ag =

maximum stress intensity is

'Sm = a0 - or=P 2

Peak Stress Intensities--values of peak stress inten-sities due to internal pressure are obtained directly from Seal-Shell-2 output data.

Alternating Stress Intensitieq--principal stret ses (c, 0, and a ) are obtained from Seal-Shell-2 output z

0 p

data for each node at each operating condition.

Stress intensities are calculated as the algebraic differences between principal stresses, or Sg=cx - a0 s Sxr " Ux - or, Ser = 00 - Gr -

x Although stress intensities are directionless, signs are maintained in the above calculations so as to insure proper combinations of stress intensities when deter-mining stress range.

Then, stress intensity range and alternating stress intensity are:

(S j)R " (S j) max - (Sij) min (Sa)ij = 1/2 (S j)R-i i

i Results of calculations, attached to this report as 6460-1 through 8 are summarized as follows:

Stress Intensity Nozzle Membrane Peak Alternating S' __ ( ksi )

Extension Sm (ksi)_

Sp (kai) a Downcomer 11.2 10.1 13.1 Biser 99 8.9 5.3 Vent 5.1 5.7 10.2 Instrument 9.1 8.7 6.2 Steam Outlet 10.0 9.6 6.3 10 y

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t 2.0- STRESS LEVELS 2.1 _ Nozzle Extensions Alternating Stress Intensities (continued)

Nozzle Membrane Paak Alternating Extension Sm (ksi)

Sp (ksi)

Sa_(ksi)

Letdown Cooling 9.o 8.7 6.4 Recirculation' Inlet 10.5

~ 101.1 6.6 Poison 91 8.8 4.9 Each of the above values are less than the allowable stress values -for the extension material of' Sm = 14.8 ksi Sp = 16.5 ksi Sae = 18 ksi where Sae is endurance limit for the material.

Calculation of stresses in the nozzle extensions are shown at the end of this report.

2.2 Internal 3 rackets Analysis.of the reactor vesse1~ internal brackets is by use of classical equations for equilibrium of forces and deter-mination of stresses in a determinate structure.

Equations presented in References 12 and 13 are used for calculation.

of torsicnal stresses in a rectangular section.

2.2.1 Core Support Bracket Leads applied'to the core support brackets include gravity loads due to weight of the thermal shield, l

top platt, and orifice, a pressure blow-off load due to pressure drop through the core,.and a horizontal seismic force of 5% of the total weight of the in-ternals.

Component weights and C.G.'s, and the pressure' blow-off load ar.e from General Ele,ctric Data - (References 14 and 15).

These loads aresdis-tributed between the six brackets as follows:

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2.2.2. Core Support Plate Brackets (continued)

The total loads, both vertical and horizontal, are assumed to be resisted by two brackets normal to the line of action of the horizontal seismic force.

The maximum calculated membrane stress intensity of

~1.4 ksi, and peak stress intensity of 15.7 ksi are below the allowable stresses of 11.8 ksi membrane and-16.2 ksi peak stress.

The maximum peak stress intensity of 15 7 ksi is also less than the 18.1 ksi endurance limit of the material.

2.2 3 Diffuser Bracket Loads applied to the Diffuser Bracket include gravity loads, a horizontal seismic force of 5% of the gravity load acting either radial or tangential to the Recir-culating Water Inlet Nozzle, and a hydraulic load due to recirculating water flow.

Magnitude of the hydraulic load was determined from the quantity of water flow through the steam drum, as specified by specifications (Ref. 2).

From these specifications, 71.8 fts/see of recirculating water is returned to the reactor vessel through two 17" I.D.

nozzles.

With the quantity of water and the are of opening known, water velocity is then calculated and flow rate determined for the case of flow against a vertical plane.

The maximum membrane stress intensity in the bracket was calculated as 0 5 ksi which is less than the 14.8 ksi.

The maximum calculated peak stress intensity of 3 9 ksi is less than the 16.2 ksi allowable peak stress intensity and the 18.1 ksi endurance limit f or the material.

2.3 Vent Nozzle Flange Analysis of the Vent Nozzle Flange requires an interaction solution.

For this solution, the nozzle and flange hub defor-mations are determined by use of the Seal-Shell-2 Computer Program (Ref.11) in the same manner as for the nozzle exten-sions.

Deformations of the flange are aetermined 'from classical equations for a ring.

In order to determine effect of bolt loads on the structure, the connec, ting pipe has been included in the interaction solution where the pipe flange was assumed to be the same as the nozzle flange and the pipe section was taken as equal to the this section of the nozzle.

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2.3 Vent 1:ozzle Flange (continued)

Loading conditions considered, and resulting temperature distributions in the..cucture were taken to be the same as for the'. nozzle extensions of Part 2.1.

Maximum calculated stress intensities are:

Membrane Stress Intensity - Em = 7.2 ksi ( Sallow = 14.8 ksi p = 5 8 ksi < Sallow = 16.2 ksi Peak Stress Intensity

-S Maximum Alternating

- Sa = 5 7 ksi < endurance Stress Intensity limit = 18.1 ksi T

30 DESIGN PRACTICES Design of internals, and their supports, for the Consumers Power -

Big Rock Plant - Steam Drum utilized design concepts originally developed, and used by Combustion Engineering, for use in con-ventional fuel power plants.

These design concepts comply with rules of the AS!43 Code applicable to the subject vessel, and minimize differential thermal loads in the internals by requir-ing that materials of different coefficients of, expansion be connected with sliding joints.

As required by specification, each of the support brackets con-sidered in this report was made of 304 stainless steel conforming to requirements of ASTM A-167-54, which has a maximum allowable carbon content of 0.08%.

Attachment of the brackets to the ves-sel was in accordance with Combustion Engineering Weld Procedure MA-88A.

Prior to welding, the stainless steel clad on the vessel weld was subjected to ultrasonic tests using a 1-1/2" grid.

Welding was with E308 filler metal conforming to ASIE Specifi-Cdtion SA 298, E308-15 Maximum interpass temperature was limited to 3000F and the vessel was subjected to a post-weld heat-treatment of 1100-1200 F for one hour per inch of vessel-thickness.

Caximum carbon content of the weld was limited to 0.06%. ' Af ter welding, the connection was cleaned with wire brushes and visually inspected.

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4.0 REFERENCES

l.'

General r,lectric ' letter, R. L. Theis to J. Harper, dated 9-15-70.

2.

General Electric Specification DP-19890,' Revision 0, Primary Steam Drum.

3 General-Electric Specification DP-19889, Revision 1, Specification for Reactor Vessel.

4.

" Stress Evaluation Criteria for Steam Drum," CE Report 6460D.

5

" Stress Evaluation Criteria for Reactor Vessel'," CE Report 6460R.

6.

General Electric Letter, R. L. Theis to J. Harper, dated-10-5-70.

7 Section I, ASx3 Code (1959), " Power Boilers".

-8.

ASME Code Case 1270N.

9 ASME Code Case 1273N.

10.

" Tentative Structural Design Basis for Reactor Vessels and Directly Associated Components," Department of Cornerce, Document PB151987, dated 4-1-58.

11.- Freid rich, " Seal-Shell A Computer Program:for the Stress Analysis of a Thick Shell of Revolution with Axisyntetric Pressures, Temperatures, and. Distributed L'oads," Bettis Atomic Power Laboratory, Pittsburgh, Pa., 1963 12. - Roark, Formulas for Stress and Strain, 4th Edition, McGraw-Hill, Kew York,1965 13 Seely and Smith, Advanced Mechanics of Materials, 1

2nd Edition, John Wiley and Sons, New York, 1952.

14.

General Electric Drawing ll4B5283, " Weights and Center of Gravity."

15 General Electric Letter, Olich to St.Cin, dated 8-17-60.

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REPORT 6460-A APPENDIX A STRESS CALCULATIONS

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2.2.1 Core Support Bracket (continued) 1.

Each bracket is assumed to resist one-sixth of the total vertical load of gravity load plus pressure blow-off load.

2.

The horizontal force is assumed to be resisted

'by the two brackets 120 away from the line of 0

action of the horizontal force.

The force on each bracket _is_ divided into-its tangential and radial components.

3 The overturning moment due to action of the horizontal force away from the brackets is assumed to be resisted by vertical forces on the brackets.

The magnitude of these forces are taken as a function of their distance along the line of action of the force from the vessel centerline.

Stresses are calculated at weld to gusset attachment lines at both the gusset to vessel weld and the-gusset to plate weld.

The maximum stress intensities are calculated for the bracket to gusset weld seition where Smembrane = 4 ksi < Sallow = 14.8 ksi peak = 11.8 ksi < Sallow = 16.2 ksi S

Alternating stresses are not calculated for the bracket since taximum alternating stresses wc 21d be equal to peak stresses and the allowable peak stresses are less than'the endcrance limit for the material.

2.2.2 Core Support Plate Bracket Loads considered in the analysis of the Core Support Plate Bracket include gravity loads, a horizontal seismic force of 5% of gravity loads, and a friction-load based on an assumed friction factor of 1.0.

Gravity loads include weights of internals as defined by General Electric (References 14 and 15).

Since the overturning moment due to the horizonta1 force acting on the weight of the internals is resihted by the Core Support Brackets (Part 2.2.1), effect 'f the seistic lead on the Core Support Plate Brackets is limited to resistance of the shear force.

12 m

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